//
// Created by 吴锐 on 2022/2/23.
//

#include<iostream>

using namespace std;

const double PI = 3.14;

class Circle{
public:
    int m_r;

    double calculateZC(){
        return 2 * PI * m_r;
    }
};

int main(){

    Circle c1;

    c1.m_r = 10;

    cout << "圆的周长: " << c1.calculateZC() << endl;


    return 0;
}